As the state of development of semiconductor components has moved to increased levels of integration, the amount of heat these devices generate has significantly increased. Components handling large quantities of electrical current such as semiconductor components generate large amounts of heat. If this heat is not adequately removed, the increased temperatures generated by the semiconductor components will damage the components.
One approach for solving the heat dissipation problem is to attach components which transfer or dissipate heat by means of heat sinks, including heat dissipation plates, fin stacks, and heat pipes, to semiconductor components. It will be appreciated that the use of the term heat sink herein includes all forms of heat dissipation devices such as fins and heat pipes. As semiconductor components get increasingly hotter, the heat dissipation devices required to cool these components likewise get larger and heavier. Both the increased size and weight of the heat sink add a risk of mechanical damage to the semiconductor component.
Heat sinks are commonly attached to semiconductor components by means of springs or clamps. Thus, the semiconductor component and the heat sink are treated as separate parts of a system. The heat sink and the semiconductor component must be fitted together with a thermal enhancer, such as a thermal pad or thermal grease, to create a low resistance thermal path to ensure a proper operating temperature for the semiconductor component. Computer systems often include multi-way computer (CPU) architectures which increase the need to add, to upgrade, or to replace semiconductor components to the computer system. Changing the semiconductor components is often done outside of the controlled manufacturing environment. The increased handling of semiconductor components increases the risk of interrupting the tightly controlled, factory installed thermal interface between the semiconductor components and the heat sink. Furthermore, in these systems access to the semiconductor component is very difficult due to the size and crowding of the heat sinks. These problems require field replaceable units with optimized thermal paths that are not interrupted in the repair or upgrade process.
As heat sinks continue to increase significantly in size and weight to accommodate the increase of heat from semiconductor components the risk of damage to the semiconductor components due to mechanical overloading is increased. Therefore, there is an increasing need to distribute the force that is created by the heat sink on the semiconductor component to minimize load conditions that could damage the semiconductor component. By way of example, the need to minimize mechanical overloading is important as mechanical overloading can cause failure of the semiconductor component.
When the semiconductor component and the heat dissipation component are handled as separate parts of a system, more particularly when the heat dissipation device must be subsequently added to the system, both more thermal and mechanical design margin are required to accommodate attachment of the independent parts. For instance, proper insertion of the semiconductor component requires accurate location and orientation of the semiconductor component with respect to the PCB, and when safe extraction of a semiconductor component is necessary typically a special tool applied with a large amount of force is required and this is especially difficult to do at a customer site without a controlled factory environment. Also, factors such as the increased integration levels that increase the electrical connections on the semiconductor component; and the separate semiconductor component and heat dissipation component both increase the need for accurate alignment of the electrical connections on the printed circuit board. Further, the increased handling, transport, and use of the semiconductor component caused by the separate component design may increase the risk of bending or otherwise damaging the area grid array on a semiconductor package. Also, treating the semiconductor package and the heat sink separately precludes early testing of the semiconductor package and the heat sink which cannot be finally tested until they are assembled together.
As will be appreciated by those skilled in the art, achieving sufficient thermal interface between the semiconductor component and the heat dissipation component requires applying a thermal interface enhancing material such as, but not limited to, a thermal pad or grease. Successful application of a thermal interface enhancing material requires a flat, clean surface to ensure a tight thermal interface between the semiconductor component and the heat dissipation component, and it is difficult to create an adequate thermal interface outside of the manufacturing environment. Therefore, when the semiconductor component and the heat dissipation component are handled as separate parts of a system, successful replacement of either component outside of the manufacturing environment is more difficult.
From the foregoing it will be apparent that there is still a need for a way to package heat sinks that adequately dissipate heat from semiconductor components, without damaging or bending the semiconductor component area grid array to ensure correct connection of the area grid array to the printed circuit board by connectors, and without imposing mechanical stress on the semiconductor component that can lead to failure. There is also still a need for packaging heat sinks and semiconductor components to enable safe maintenance of the semiconductor components, including removal and addition of semiconductor components outside of the manufacturing environment.